1. Field of the Invention
This invention relates to polyolefin foamed fibers and a process for producing the same. More particularly it relates to polyolefin composite fibers of side-by-side type or sheath-and-core type wherein foamed cells are contained only in one of the components of the fibers and a part of the cells burst open on the fiber surface, and a process for producing the same.
2. Description of the Prior Art
Polyolefin fibers such as fibers of polypropylene, polyethylene or the like have an advantage of small density and great strength, but on the other hand, they have a drawback of giving a feeling called generally as a "numeri" feeling in Japanese (or a slimy feeling) or a waxy feeling. Particularly in the case of fibers of small fineness, a problem that this slimy feeling is promoted has been raised. In order to overcome this drawback, the so-called irregular shape fibers taking various forms of fiber cross-section other than circular form have been proposed, but any satisfactory products have never been obtained.
The present inventors have made strenuous efforts for developing polyolefin fibers having a small fineness without any slimy feeling, and as a result have found that when fibers are foamed and a part of the resulting foamed cells is caused to burst open on the fiber surface, it is possible to obtain polyolefin fibers having a suprior feeling.